MANHATTAN, Kan. -- Repeated Gallup polls have put gardening as the No. 1 U.S. leisure-time activity. Yet, the nation’s gardeners may be harvesting more than they know.

Evidently, gardening is good for people, as well as plants. That fact is emerging clearly from research in such diverse fields as medicine, psychology, urban housing and horticulture.

"Research on the people-plant connection has yielded only positive results -- no matter if the plant life is a single flower on a desk or a group of trees in a botanic garden," said Richard Mattson, director of the horticultural therapy program at Kansas State University.

K-State’s program became the first of its kind in 1971, with strong support from Topeka’s Menninger Foundation. It now is the only U.S. program offering B.S. through Ph.D. degrees and is a recognized center for research into horticulture’s therapeutic effects.

The physical benefits may be easiest to prove.

"Just walking through a garden can reduce blood pressure," Mattson said. "If you pick up and use a shovel or hoe, you gain strength benefits. If you use those tools with some enthusiasm or determination, you also get aerobic benefits similar to those in jogging or working out with exercise equipment."

Health magazine recently reported a University of Arkansas finding that people who garden at least once a week have higher bone density than those who swim, jog, walk or do aerobics.

"For people with limits created by age or handicap, however, the passive benefits of gardening are just as important as the active exercise," said Mattson, who works with K-State Research and Extension, and is a member of the university's teaching faculty.

Indoors, hospital studies have shown that just seeing plants (and/or their flowers) can make a difference. Patients with plants in view recovered more quickly from major surgery. They needed significantly less pain killer – even if the plants were outside a window, rather than in the patient’s room.

NASA studies discovered foliage plants, such as the philodendron and spider plant, reduce indoor air pollutants, too.

K-State’s horticultural therapists now are measuring biomedical responses to plants, studying the reactions of the human brain, heart, and sensory and immune systems.

Researcher Eunhee Kim has found, for example, that red-flowering geraniums can shorten the time women need to recover from stress. Joe Laviana has proven a single plant or flower in an office has the same psychological effect as a roomful of plants and flowers.

"Dr. Laviana’s work builds on earlier, nationwide findings that plants increase productivity. They reduce both stress and absenteeism. They create a feeling that the workplace is a safer, more pleasant place to be," Mattson said.

Takashe Tomono, now a student in the K-State degree program, ties this impact to that found in original-style Zen Buddhist gardens in Japan.

"We don’t use many flowers for coloring in the garden. Usually we use a variety of stones and green plants, some of which change their leaf colors to red, orange or yellow in the fall," he said. "These simple items make tranquil space. People from Japan and other countries visit these quiet and calm temple gardens and enjoy a cup of green tea."

Mattson took the point a step further: "The old saying is, ‘An apple a day keeps the doctor away.’ But it’s becoming increasingly apparent that growing the apple tree or even just looking at it occasionally can accomplish much the same thing. Few things so clearly aid both physical and emotional well-being."